Method of blasting rock



(No Model;

G. M. GITHENS.

V METHOD OF BLASTING ROCK. A No. 512,816. 4 Patented Jan. 16. 1894.

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GEORGE M. GITHENS, OF BROOKLYN, NEW YORK.

METHOD OF BLASTlNG ROCK.

SPECIFICATION formng part of Letters Patent No. 512,816, dated January16, 1894.

Application filed March 11,1893.

To all whom it may concern:

Be it known that I, GEORGE M. GITHENS, a citizen of the United States,residing at Brooklyn, in the county of Kings and State of New York, haveinvented an Improvement in Methods of Blasting Rock, of which thefollowing is a specification.

Before my invention blast holes had been drilled in stone to the desireddepth and a charge of explosive material introduced into the bottom ofthe hole and an expansion air chamber left between the blast and thetamping, so that when the charge was fired the gases would expand intothe space above the explosive material and Increase the area of pressureand cause the rock to be splitin the desired manner. This mode ofblasting has been made use of in cylindrical holes as well as in holeschanneled on their opposite surfaces. In this mode of blastingdifficulty has been experienced, especially when blasting sandstone,marble or similar materials that are comparatively soft. This difficultyhas been two-told: first, the intensity of the explosion has injured, bydisintegration, the stone immediately adjacent to the blast, and whenthe blast is exploded the expansion of the gases is upwardly toward thetamping and the accumulation of pressure commences against the underside of the tamping; hence the rock is split at two points almostsimultaneously; that is to say, itis split immediately adjacent to theexplosion and immediately adjacent to the under side of the tamp-` ing,and these two cracks do not always run together but frequently are at anangle to each other and extend past each other; hence the stone betweenthe two cracks is Valueless. v

The object of my present invention is to insure the cleaving of thestone in the proper direction and to prevent the formation of twocracks, so that only one line of cleavage is started and continued bythe expansive action of the gases generated in the explosion. XVith thisobject in view I drill the rock in any ordinary manner, either with acircular hole or channeled along one or more of its sul-faces, or elsethe rock is drilled with an elliptical or other shaped hole, asrepresented in my Patents Nos. 371,679 and 4:86,101, as

Serial No. 465506. (No model.)

my improvements are not limited to any particular shape of hole. I makeuse of a canister or powder holder that is conparatively long and thinand of a Width corresponding or nearly so to the interior diameter ofthe hole, and in conseqence of this shape of powder holder the explosivematerial is cansed to occupy a greater length or distance in the blasthole, and in addition to this, expansive air chambers are left withinthe hole at each side of the powder holder or canister. The consequenceof this Construction is that when the explosive material is fired theline of cleavage is perpendicular or nearly so to the plane of thelongest diameter of the cartridge case; that is to say, when theexplosion occurs the gases do not act as powerfully upon the surfaces ofthe stone that are close to the canister as they do upon the surfaces ofthe stone at the more distant places in the air chamber at the oppositesides of the powder canister.

In `the drawings I have represented in Figure l a sectional plan View ofthe canister with the adjacent air chambers, and in Fig. 2 I haverepresented a longitudinal section of the rock and a transverselongitudinal section of the powder holder, and Fig. 3 shows myimprovement with a hole that is of greater diameter in one directionthan the other.

A represents the rock or stone to be split, B the hole therein which'may be of any desired shape, and C the canister or powder holder whichis fiat andthin, the greater diameter of the powder holder correspondingor nearly so to the interior diameter of the bore in the rock, so thatthere are expansive air chambers E and F, one at each side of the powderholder or canister, and the tamping G is to extend down to the upper endof the powder holder or nearly so, and the powder may be fired in anydesired manner. I however usually prefer to employ a fuse K passing downthrough one of the air chambers so as to commence the explosion of thepowder or similar material at the bottom end of the charge. I find thatthe line of clcavage is at right angles to a plane passing through thelonger diameter of the powder holding case, namely upon the line H, andthis appears to arise in consequence of the powder holding case beingdisrupted nearly in the line H,

and theforce of the explosion accumulating and concentrating upon theline H or nearly so; hence the crack in the rock will be a single crackcommencing at one end or the other of the air chambers and extendingfrom the point of commencement so that the rock is split without thedefects heretofore inseparablejrom the formation of the two cracks ateach side of the blast hole, and much less stone is wasted by myimprovement than when the charge is fired in the modes heretofore usual.

I am aware that cartridge cases have been made elliptical, but when thesame are intro` duced in the blast hole, sand or similar tampingmaterial has been poured in to fill the spaces between the cartridgecase and the rock, and in this instance there is no expansive chamberfor the gases, and the line of cleavage of the rock is uncertain, but itusually takes place in a plane passing through the longer diameter ofthe elliptical Cartridge case.

In cases where the blast hole is longer in one direction than the other,as in my Patent No. 486,101, the Cartridge case may be cylindrical, asshown in Fig. 3. Theair chambers E' F' at opposite sides of saidCartridge C' act in the manner before described and the line of cleavageis at H.

Iclaim as my invention- 1. The method herein specified of blasting rock,consisting in drilling a hole in the rock 3 5 and introducing thereintothe explosive material in a ,ca-se or holder that is flat and com-`paratively thin, such case or holder corresponding or nearly so in itswidth to the diameter of the blast hole, so as to leave expansive airchanbers at each side of the cartridge, whereby the action of a givencharge of powder is distributed over a greater length in the blast holeand the line of cleavage is determined by the direction that thecartridge stands in relation to the hole, substantially as set forth.

2. The method herein specified of blasting rock, consisting in drillinga hole and introducing thereinto a cartridge having a case that is of awidth corresponding or nearly so to the diameter of the hole andsufiiciently thin to leave expansive air chambers at each side of suchcase, and igniting the cartridge at its lower end 'so as to commence theline of cleavage from the bottom of the hole and in a plane at rightangles to the longer diameter of the Cartridge case, substantially asset forth.

3. The method herein specified of blasting rock, consisting in drillinga hole in the rock and introducing thereinto a cartridge of such a shapethat a longitudinal air chamber is left at each side ot the Cartridgebetween the same and the rock and exploding such cartridge,substantially as specified.

Signed by me this 9th day of March, 1893.

GEO. M. GITI-IENS.

Witnesses:

GEO. T. PINCKNEY, A. M. OLIVER.

